Among the risk factors for alcoholism in humans is a low initial sensitivity and/or a rapid development of tolerance to ethanol. These behavioral reactions can be modeled in animals. One such model is Alcohol Tolerant (AT) and Alcohol Non-Tolerant (ANT) lines of rats that were selectively bred for genetic tolerance to a low, ataxic dose of ethanol. These animals have been transferred to the University of Colorado and we will compare the genetic characteristics of these animals with those that we have selectively bred to genetic tolerance to a high, anesthestizing dose of ethanol, the High Alcohol Sensitive (HAS) and Low Alcohol Sensitive (LAS) rats. We will locate and compare Quantitiative Trait Loci in these two groups of animals as well as carry out comparisons on the development of tolerance to a number of behavioral effects of ethanol. In addition we will make the AT and ANT rats available to researchers in this country and abroad for their studies. The data generated along with similar data from studies in mice will be useful in the search for the genes that underlie the risk factors for alcoholism in humans.